PLATE XXIV. 

 < Jyphaspis, coelebs. 



Page 161. 

 Fie. I. An imperfect specimen, the drawing having been made Fn m a gutta-percha impression of the in- 

 ternal surface, showing thegi-eal length of the genal spine, and the broad and rapidlj tapering 

 a\is. Enlarged to three diameters. 



Lower Helderberg group. Schoharie, Sehohaiie county. 



( !} PHASPIS STEPHANOPHORA. 



Page 1«. 

 Fig. -'. A cephalon, having the cheeks slightly depressed along the sutures; showing the upper row of 

 marginal spines. Drawn from a natural cast of the internal surface Enlarged to three 

 diameters. 

 Kg. 3. The same, drawn in profile; showing the elevation of the glabella, the convexitj of the frontal 

 area. The figure is slightly restored to show the double row of marginal spines. 

 Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 4. An imperfect cephalon, showing the liases of the upper row of marginal spines, and of the thi-ee 

 short spines on the occipital ring. Enlarged to three diameters. 

 Corniferous limestone. Canandaigua, Ontario county. 

 Fig. .". The internal surface of an imperfect cephalon, showing the length of the upper row of marginal 

 spines. Enlarged to three diameters. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 6. An imperfect cephalon, showing the bases of the upper row of marginal spines and two spines of 



the lower row. Enlarged to three diameters. 

 Fig. 6a. Outline profile of the same, with the marginal spines restored. 



Corniferous limestone. Canandaigua, Ontario county. 



Cypkaspis minuscula. 



rage 110. 

 See Plate 20. 



Fig. 7. The intra-sutural portion of the cephalon. Enlarged to throe diameters. 



Schoharie grit. Near Clarksville, Albany county. 

 Fig. 8. A similar fragment, showing the tubercles on the occipital ring. Enlarged to three diameters. 

 Fig. Sa. Outline profile of the same, showing the elevation of the glabella and the slope of the frontal area. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 9. An entire individual, preserved as an internal cast in decomposed chert ; showing the general 



form and proportions of the parts. Enlarged to three diameters. 

 Fig. 10. The same, drawn in profile. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 11. A larger and less perfect individual. Enlarged to three diameters. 



Corniferous limestone. Canandaigua, Ontario county. 

 Pig. 12. An internal impression, showing the hypostoma slightly displaced from its normal position. En- 

 larged to three diameters. 



Corniferous limestone. Canandaigua, Ontario county. 



Cyphaspis DIADEMA. 



Page 141. 



Fig. 13. A portion of the cephalon, showing the strongly tubercled surface, and the single row of pustules 



across the frontal area. Enlarged to six diameters. 

 Fig. 13a. Outline profile of the same, showing the depressed frontal area, and the elevate, I margin. 

 Corniferous limestone. Canandaigua, Ontario county. 



